Abstract:
We observed a colossal dielectric response of small (5–10 nm) oxygen-deficient Hf𝑥Zr1−𝑥O2 nanoparticles (𝑥=1–0.4), prepared by solid-state organonitrate synthesis. The effective dielectric permittivity of the pressed Hf𝑥Zr1−𝑥O2 nanopowders has a pronounced maximum at 38–88∘C, the shape of which can be fitted by the Curie-Weiss type dependence modified for the diffuse ferroelectric-paraelectric phase transition. The maximal value of the dielectric permittivity increases from 1.5×103 (for 𝑥=1) to 1.5×105 (for 𝑥=0.4) at low frequencies (∼4 Hz), being much smaller, namely, changing from 7 (for 𝑥=1) to 20 (for 𝑥=0.4) at high frequencies (∼500 kHz). The frequency dispersion of the dielectric permittivity maximum position is almost absent; meanwhile, the shape and width of the maximum changes in a complex way with increase in frequency. The temperature dependencies of the dielectric permittivity and resistivity are almost mirrorlike turned over with respect to each other, which means that all their features, such as position and shape of maxima, plateau, minima, and inflexions, almost coincide after the mirror reflection with respect to the temperature axis. These correlations of resistivity and dielectric permittivity are well described in the Heywang barrier model applied together with the variable range hopping conduction model in semiconducting ferroelectrics. Ferroelectriclike behavior of the small oxygen-deficient Hf𝑥Zr1−𝑥O2 nanoparticles is expected from the Landau-Ginzburg-Devonshire approach and density functional theory calculations. Obtained results may be useful for developing silicon-compatible functional nanomaterials based on Hf𝑥Zr1–𝑥O2 nanoparticles.
Title: Colossal dielectric response of Hf𝑥Zr1−𝑥O2 nanoparticles
Authors: Oleksandr S. Pylypchuk, Victor V. Vainberg, Vladimir N. Poroshin, Oksana V. Leshchenko, Victor N. Pavlikov, Irina V. Kondakova, Serhii E. Ivanchenko, Lesya P. Yurchenko, Lesya Demchenko, Anna O. Diachenko, Myroslav V. Karpets, Eugene A. Eliseev, Anna N. Morozovska
Reference: Phys. Rev. Materials 9, 114412, 2025
